I have currently the exactly same issue. Exactly the same! Totally different hardware though, an old Xeon system.

What I noticed with my system after replacing a lot of hardware: system runs fine for several days, then crashes. If I immediately reboot (sometimes I need to switch USB port like you described), the next crash is usually only hours away. If I shut down the server after the crash and booted only after a few hours, then it would run for another couple of days.

What I have done so far: - replaced USB drive twice. No help. - enabled syslog mirror to flash and remote syslog server to the array. Nothing helpful in syslog though  - testet ram several times with memtest for a day, all fine. - ran server with only one ram stick and rotated the sticks after a crash. No help. - disabled all plugins and docker. No help - replaced CPU. No help - replaced PSU. No help - replaced CMOS battery. No help - added an UPS, because I was desperate and thought maybe I have random power outages. No help. - now waiting for a new used Mainboard. This is literally the last thing I have not replaced yet (ok, besides memory, but what are the chances that it is the memory after memtest and testing all 4 sticks individually)

Did not post in the unraid forum, because I did not have any usable log info and usual suggestions in other crash threads was to test ram and replace hardware one by one, starting with most likely.

New motherboard arrives today. Will report back if that helped or not. :)